I have a C-390 and I want to know my GPH. Does anyone use a standard rate or can someone forward the calculation please.
Wes
Summer Wind
Wes
Summer Wind
Fuel consumption rate
- Thread starter Gabrielwes
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Diesel engines use about one gal per hour per 18 horsepower WOT.
40hp / 18 = 2.22 So that looks like 2¼ GPH WOT.
If cruise is ¾ WOT then cruise would be about 1¾ GPH.
Yanmar publishes fuel consumption curves. Rules of thumb. Cruise at 80 percent of max continuous rpm. Cruise speed will be 1.2 Times Square root of waterline length - flat water. Power will be 50 percent of max power and fuel consumption will be 1 gallon per eighteen horsepower. Most cruisers have 2.5 hp per thousand pound light displacement.
Biggest caveat is correct prop pitch. But bottom and other stuff may affect it
Biggest caveat is correct prop pitch. But bottom and other stuff may affect it
Your fuel consumption number sounds high to me. On my previous boat, a Catalina 30, I had a Universal M25XP, which was 23 hp. It only burned about half a gallon per hour. On my boat before that I had a Universal M18, which was maybe 15 hp (?) and it burned a bit over a quarter gallon per hour. And in both instances I typically ran the engine at about 80% of max continuous rated RPM.
Alan
Your numbers should be right. At 80% RPM which is about 50% power a 23 hp engine should be running at about 11.5 horsepower which is about .6 gph.
Your numbers should be right. At 80% RPM which is about 50% power a 23 hp engine should be running at about 11.5 horsepower which is about .6 gph.